Communication Options Of The Cpu - Siemens SIMATIC S7-300 Series Reference Manual

Behavior of Clock in POWER OFF Mode
The following table shows the clock behavior with the power of the CPU off,
depending on the backup:
Backup
With
backup
battery
With
accumulator
None
1.2

Communication Options of the CPU

The CPUs offer you the following communication options:
PLC S7-300, CPU Specifications CPU 312 IFM to CPU 318-2 DP
A5E00111190-01
CPU 314 to 318-2
The clock continues to operate in
power off mode.
The clock continues to operate in
power off mode for the backup time
of the accumulator. When the power
is on, the accumulator is recharged.
In the event of backup failure, an
error message is not generated.
When the power comes on again,
the clock continues at the clock time
at which the power went off.
At POWER ON, the clock continues
to operate using the clock time at
which POWER OFF took place.
Since the CPU is not backed up, the
clock does not continue at POWER
OFF.
CPU 312 IFM and 313
At POWER ON, the clock continues
to operate using the clock time at
which POWER OFF took place.
Since the clock does not have a
power buffer, it does not continue to
run in POWER OFF mode.
CPUs
1-11